On Fri, Jul 12, 2019 at 09:06:40AM +0200, Thomas Gleixner wrote: > On Fri, 12 Jul 2019, Ming Lei wrote: > > vmalloc() may sleep, so it is impossible to be called in atomic context. > > Allocations from atomic context should be avoided wherever possible and you > really have to have a very convincing argument why an atomic allocation is > absolutely necessary. I cleaned up quite some GFP_ATOMIC users over the > last couple of years and all of them were doing it for the very wrong > reasons and mostly just to silence the warning which is triggered with > GFP_KERNEL when called from a non-sleepable context. > > So I suggest to audit all call sites first and figure out whether they > really must use GFP_ATOMIC and if possible clean them up, remove the GFP > argument and then do the vmalloc thing on top.
Hello Thomas and Ming, It looks like the following call sites are atomic: drivers/crypto/qce/ablkcipher.c:92: ret = sg_alloc_table(&rctx->dst_tbl, rctx->dst_nents, gfp); drivers/crypto/ccp/ccp-crypto-aes-cmac.c:110: ret = sg_alloc_table(&rctx->data_sg, sg_count, gfp); drivers/crypto/ccp/ccp-crypto-sha.c:103: ret = sg_alloc_table(&rctx->data_sg, sg_count, gfp); drivers/spi/spi-pl022.c:1035: ret = sg_alloc_table(&pl022->sgt_rx, pages, GFP_ATOMIC); drivers/spi/spi-pl022.c:1039: ret = sg_alloc_table(&pl022->sgt_tx, pages, GFP_ATOMIC); The crypto ones are conditionally made atomic depending on the presence of CRYPTO_TFM_REQ_MAY_SLEEP. Additionally, the following allocation could be problematic with kvmalloc: net/ceph/crypto.c:180: ret = sg_alloc_table(sgt, chunk_cnt, GFP_NOFS); This is a snippet from kvmalloc: /* * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables) * so the given set of flags has to be compatible. */ if ((flags & GFP_KERNEL) != GFP_KERNEL) return kmalloc_node(size, flags, node); Use of GFP_NOFS in net/ceph/crypto.c would cause kvmalloc to fall back to kmalloc_node, which could cause problems if the allocation size is too large for kmalloc_node to reasonably accomodate. Also, it looks like the vmalloc family doesn't have kvmalloc's GFP_KERNEL check. Is this intentional, or does vmalloc really not require GFP_KERNEL context? Thanks, Sultan